Richard Stolzenberger

Growth of large single crystals of KTiOPO4 (KTP) from high-temperature solution using heat pipe based furnace system

Abstract A process is reported for crystal growth of KTiOPO4 from its solution in K6P4O13 using a seeded, slow cooling technique. A new furnace system is reported for use in the process, its key feature being a heat pipe providing for a high degree of spatial temperature uniformity throughout the growth solution. Initial surface dissolution appears necessary to achieve flaw-free growth immediately off a seed. Avoidance of solution inclusion flawing in advanced stages of growth requires a crystal orientation configuration and rotation pattern that does not give rise to stable regions of uncirculating growth solution. Through the process, 10-day growth runs routinely produce flaw-free crystals large enough to yield plates 10 × 10 × 7 mm3 oriented in the optimal direction for second harmonic generation having properties measured to be at least as good as KTiOPO4 grown by other methods.

Nonlinear optical properties of flux growth KTiOPO 4

The properties of large flux grown KTiOPO(4) second harmonic generators were measured. A technique which provides a sensitive assessment of crystal uniformity is described. Optically perfect second harmonic generation crystals of up to 1 cm(3) were found to have nonlinear optical properties comparable with those grown by other methods. A Q-switched Nd:YAG laser was used to determine temperture acceptance widthlength product (20 degrees C cm), angular acceptance width-length product (13 mrad cm), and doubling efficiency (50%). Spectral bandwidth (4.5 A cm) and wavefront distortion ((1/4) wave at 633 nm) were also measured. The dependence of these properties on crystal homogeneity is demonstrated.

Type II sum frequency generation in flux and hydrothermally grown KTP at 1.319 and 1.338 mu m

Type-II, noncritically phase-matched, sum-frequency generation by mixing of the 1.319- and 1.338- mu m lines of a Q-switched Nd:YAG laser with their second harmonics is discussed. Results are presented for KTP crystals grown by both the hydrothermal and the flux technique. A temperature-acceptance width-length product of 8.5+or-0.5 degrees C-cm was determined. Type-II critical phase matching at room temperature, for three different propagation/polarization orientations, is also demonstrated. The differences in the angles required for phase matching between crystals grown by the different techniques are quantified.<<ETX>>

Seeded femtosecond optical parametric amplification in the mid-infrared spectral region above 3 µm

Femtosecond optical parametric amplification that results in microjoule mid-infrared pulses at wavelengths exceeding 3 mum is demonstrated. Narrow-band quasi-cw seeding at the signal wavelength is applied to ensure the generation of nearly transform-limited femtosecond pulses at the idler wavelength. The broad bandwidth of the parametric amplification provided by pumping with femtosecond pulses from a Ti:sapphire regenerative amplifier at high intensity results in idler pulse durations shorter than the pump pulse length. The potentials of three nonlinear optical crystals that belong to the potassium titanyl phosphate family are comparatively studied. At 1-kHz repetition rate our all-solid-state system produces highly synchronized ~100-fs pulses in the spectral range between 3 and 4 mum.

Pump wavelength tuning of a near-infrared optical parametric oscillator

Optical parametric conversion in a potassium titanyl phosphate crystal with a tunable alexandrite laser was investigated as a function of pump wavelengths in the 700-800-nm region. Threshold energies and slope efficiencies for a doubly resonant oscillator configuration were measured for pump wavelengths of 744, 766, and 780 nm. Phase-matching conditions and a theoretical analysis using Sellmeiers equations provide good agreement with experimentally measured values of signal and idler wavelengths as a function of the pump wavelengths.